You Are What You Train
Most players understand this, but don't really absorb how important this simple lesson is. Here are two examples.
On Monday I was teaching the backhand loop to a beginning/intermediate class. I don't have a particularly good backhand loop, so I had assistant coach John Hsu demonstrate it. It seemed a good time to also teach the blocking, so I went over that as well as I blocked John's loop. Then I pointed how at the higher levels many players topspin their blocks, essentially mini-loops, and explained how while I blocked the normal way (relatively flat), John almost always topspins his blocks.
To demo this, I looped forehands from my backhand corner to his backhand and he backhand topspin blocked away. The rally went on for a time, and then I ripped one down the line to his forehand. John reacted quickly and forehand blocked to my wide forehand. I raced over and looped down the line to his backhand. He blocked back wide to my backhand, but not too aggressively. Now I'd just been teaching the backhand loop, and you'd think that at 54 years old I'd play an easy backhand winner (as John and most "top" players would have), but no - I did what I'd trained myself to do way back in the late 1970s and 1980s, and ran all the way over from my wide forehand to my wide backhand and ripped a forehand winner down the line for a winner. Afterwards neither I nor John nor the players in the class could believe I'd gotten over there so fast - and I was sort of surprised as well. But it was a simple matter of balance on the previous shot so I could recover quickly, proper footwork technique that got me there quickly, and the automatic instincts that led me to attempt that shot. (I just wish I could still do shots like that regularly in matches - technique aside, my legs aren't as fast anymore, mostly due to knee problems.)